Final answer:
The statement in the question is false; Strongyloides stercoralis causes strongyloidiasis and is different from large strongyles, which affect horses.
Step-by-step explanation:
The statement that "Fourth stage larvae roundworms that may wander extensively through the body of the horse before becoming adults are considered large strongyles" is false. The larvae described in the question are from Strongyloides stercoralis, which cause strongyloidiasis. These roundworms penetrate the body through the skin and end up in the intestine, but they are not classified as large strongyles. Large strongyles are actually a different group of nematodes that are particularly harmful to horses, known for causing extensive damage as they migrate through various organs.
Roundworms (nematodes) are a diverse group, and while Strongyloides stercoralis is indeed a nematode, the characteristic wandering larvae that can extensively move throughout the host's body before maturing are specifically associated with Strongyloides rather than large strongyles.